How much turbulence is too much?

You seem to use percentage power as a primary input. How do you judge that?

In order to target a desired airspseed, I try to recall my performance chart
and just pick the appropriate RPM, without thinking about "percentage
power"; I'm interested to know if you find that thinking about "percentage
power" has some advantage.

I've only seen engine performance charts that give percentage power from
pressure altitude and rpm. Do you really do that calculation in order to
set desired percentage power from RPM, or are you just estimating?

"David Megginson" wrote in message
...
"Marty Ross" writes:

In reviewing the Warrior II's performance numbers in preparation for
my recent trip across California, I realized that Va would be much
lower than I had always considered it (given that it's just me
inside, with gas burning off towards reserve only). The Va that's
written on my lapboard is 111 KIAS, however that's figured at gross
weight (2325 lbs). It goes down all the way to 88 KIAS (at 1531
lbs.), so I was surprised to see how slow I need to go, according to
normal procedures, when it gets turbulent in the Warrior (e.g., I
should slow down to mid-90's)!

Or, to put it differently, you should throttle back to 55-65% power.
While it's not exact, on the Warrior II 55% power will tend to give
about 90 kias, 65% power will give about 100 kias, and 75% power will
give about 110 kias, whatever your density altitude (the IAS/CAS does
decrease slightly with altitude, but by only a few knots).

I specifically note this POH's references to "good operating
practice used in all aircraft" and "the structural loads caused by
gusts" as they relate to another question (of turbulence causing
increased airframe stress) on this thread.

Exactly: typically, Va will be double Vs. The Cessna 172P, for
example, has a lower Vs than the PA-28-161 (about 44 kias/50 kcas, vs
50 kias/57 kcas), so its Va is lower as well.


All the best,


David

--
David Megginson, , http://www.megginson.com/